e34 535 pistons

[PVAmenda]

First time in. Bought '91 535 recently online. Ticking noise similar to lifter (head replaced by previous owner, and correct install confirmed by my local shop), but sound appears to be related to BMW service bulletin focused on piston fitment (clearance issues, wrist pin?). Louder on acceleration, quiet while off-load. Any more info on this, and what is the failure mode if any? Thanks!

[Kalevera]

Poorly adjusted valves (likely) or loud/old/dirty injectors (also very likely).

Some ticking noise is normal for the M30. It sounds like a sewing machine. Too much is an issue. I'm about to replace my injectors in hopes of fixing a lot of the noise.

best, whit

[Robin-535im]

Common advice to all new M30 owners is to open up the valve cover, adjust the valves, and replace the banjo bolts. Sound may be injectors or valves, and M30's need valve adjustments every 15k miles at the minimum, more often if you like the smell of Mobile 1 on your hands :) .

Bruno's site (http://www.bmwe34.net/) has all the info you will need on both issues. Valves are notoriously loud on M30's as Lowell mentioned, as are injectors. You can use a mechanic's stethoscope to listen to the injectors and see if that is it.

Banjo bolts are in there real loose (torque spec is a few inch lbs I think) and they work loose after a while, causing the cam shaft to operate without oil. People sometimes buy a 535, take off the VC and see them laying around in the valve area! Not good.

Don Gale (http://www.nmia.com/~dgnrg/page_2.htm) sells a really cool upgrade for this that will keep them in place for ever.

HTH

- Robin

[Bill R.]

describe, are you sure you don't have a cracked exhaust manifold or blown gasket at the exhaust manifold or at the exhaust flange? This will sound like a tapping noise and will get louder on acceleration and quieter off pedal. Piston slap doesn't usually change during acceleration either, more temp related such as when the engine is warming up... Wrist pin bushings can tap like your describe but its not likely... I'd check the exhaust manifold and gaskets first.








First time in. Bought '91 535 recently online. Ticking noise similar to lifter (head replaced by previous owner, and correct install confirmed by my local shop), but sound appears to be related to BMW service bulletin focused on piston fitment (clearance issues, wrist pin?). Louder on acceleration, quiet while off-load. Any more info on this, and what is the failure mode if any? Thanks!

[PVAmenda]

Thanks for the info so far...

Head & valves have been checked & adjusted. Haven't cheked exhaust system in depth, tho. Any body ever heard of the piston issue noted in the BMW service bulletin I referenced, and does it just stay noisey, or does the pin eventually fail or crack the piston skirt? Thanks!

[Bill R.]

the first 3 to 5 minutes of operation under load.
They are referring to a piston skirt to cylinder wall issue not a wrist pin clearance issue... Typically piston slap from excessive clearance can go on for a very long time without much harm, especially since it tends to go away after the piston heats up and expands to fit the cylinder.Forged pistons are known for this knocking when cold since forged have a different expansion rate than cast pistons..













Thanks for the info so far...

Head & valves have been checked & adjusted. Haven't cheked exhaust system in depth, tho. Any body ever heard of the piston issue noted in the BMW service bulletin I referenced, and does it just stay noisey, or does the pin eventually fail or crack the piston skirt? Thanks!

[PVAmenda]

Looks like I'll be digging into the exhaust system next...

Thanks to all!